https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Thu, 14 May 2026 09:50:31 GMT 2026-05-14T09:50:31Z http://hdl.handle.net/10985/13276 Influence of loading conditions on the overall mechanical behavior of polyether-ether-ketone (PEEK) ABBASNEZHAD, Navideh; KHAVANDI, Alireza; ARABI, Hossein; SHIRINBAYAN, Mohammadali; TCHARKHTCHI, Abbas; FITOUSSI, Joseph Testing methods have been developed to compare the mechanical responses and failure behavior of polyether-ether-keton (PEEK) thermoplastic polymer; under quasi-static, high strain rate tensile tests and fatigue loading. Tensile tests were performed with the strain rates varying from 0.0003 s−1 to 60 s−1 and at different temperatures to compare the flow characteristics of the samples undergone various testing conditions. Fatigue tests at different amplitudes and frequencies were also performed to evaluate the temperature rise during cyclic loading and its effect on the fracture behavior. Results show that dynamic tension, in comparison with quasi-static behavior, causes brittle fracture; whereas under fatigue test at high frequencies and loading amplitudes the material behaves not only a more ductile behavior but also it clearly shows the influences of induced self-heating in the modulus and mechanical properties of the PEEK were significant. So the major aim of this article is to discuss about the induced temperature and its effect on the fracture surface. Thermal fatigue has a very significant role in increasing temperature and reducing fatigue life; from there it is necessary to know the conditions at which thermal fatigue happens and also the amount of energy which is consumed. Obtained equation from the experimental results and calculations can estimate the energy dissipation in the fatigue tests which is as a function of cycle and frequency. Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/10985/13276 2018-01-01T00:00:00Z ABBASNEZHAD, Navideh KHAVANDI, Alireza ARABI, Hossein SHIRINBAYAN, Mohammadali TCHARKHTCHI, Abbas FITOUSSI, Joseph Testing methods have been developed to compare the mechanical responses and failure behavior of polyether-ether-keton (PEEK) thermoplastic polymer; under quasi-static, high strain rate tensile tests and fatigue loading. Tensile tests were performed with the strain rates varying from 0.0003 s−1 to 60 s−1 and at different temperatures to compare the flow characteristics of the samples undergone various testing conditions. Fatigue tests at different amplitudes and frequencies were also performed to evaluate the temperature rise during cyclic loading and its effect on the fracture behavior. Results show that dynamic tension, in comparison with quasi-static behavior, causes brittle fracture; whereas under fatigue test at high frequencies and loading amplitudes the material behaves not only a more ductile behavior but also it clearly shows the influences of induced self-heating in the modulus and mechanical properties of the PEEK were significant. So the major aim of this article is to discuss about the induced temperature and its effect on the fracture surface. Thermal fatigue has a very significant role in increasing temperature and reducing fatigue life; from there it is necessary to know the conditions at which thermal fatigue happens and also the amount of energy which is consumed. Obtained equation from the experimental results and calculations can estimate the energy dissipation in the fatigue tests which is as a function of cycle and frequency. http://hdl.handle.net/10985/17940 Viscoelastic properties of multi-walled carbon nanotube/epoxy composites using two different curing cycles MONTAZERI, Arash; KHAVANDI, Alireza; JAVADPOUR, Jafar; TCHARKHTCHI, Abbas Along with carbon nanotubes (CNT) morphology, impurity, and functionalization, polymer curing cycle is another important factor in determining the mechanical properties of the CNT/polymer composite samples. This work investigates the effect of two different curing cycles on mechanical and thermo-mechanical properties of the nanotube in the composite in order to optimize the curing condition in term of time and temperature. Nanocomposite samples were prepared by mixing multi-wall carbon nanotubes with epoxy resin using sonication method. The mechanical and viscoelastic properties of the resulting composite samples were evaluated by performing tensile and dynamic mechanical thermal analyses (DMTA) test. The results indicate that the mechanical and viscoelastic properties of pure epoxy and composite samples have been affected by the condition curing process. Concerning viscoelastic modeling, the COLE-COLE diagram has been plotted by the result of DMTA tests. These results show a good agreement between the Perez model and the viscoelastic behavior of the composite. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/10985/17940 2010-01-01T00:00:00Z MONTAZERI, Arash KHAVANDI, Alireza JAVADPOUR, Jafar TCHARKHTCHI, Abbas Along with carbon nanotubes (CNT) morphology, impurity, and functionalization, polymer curing cycle is another important factor in determining the mechanical properties of the CNT/polymer composite samples. This work investigates the effect of two different curing cycles on mechanical and thermo-mechanical properties of the nanotube in the composite in order to optimize the curing condition in term of time and temperature. Nanocomposite samples were prepared by mixing multi-wall carbon nanotubes with epoxy resin using sonication method. The mechanical and viscoelastic properties of the resulting composite samples were evaluated by performing tensile and dynamic mechanical thermal analyses (DMTA) test. The results indicate that the mechanical and viscoelastic properties of pure epoxy and composite samples have been affected by the condition curing process. Concerning viscoelastic modeling, the COLE-COLE diagram has been plotted by the result of DMTA tests. These results show a good agreement between the Perez model and the viscoelastic behavior of the composite. http://hdl.handle.net/10985/9894 3D Model for Powder Compact Densification in Rotational Molding ASGARPOUR, Monir; KHAVANDI, Alireza; TCHARKHTCHI, Abbas; BAKIR, Farid; KHELLADI, Sofiane During rotational molding, a loosely packed, low-density powder compact transforms into a fully densified polymer part. This transformation is a consequence of particles sintering. Powder compact density evolution of the polymer powder is measured experimentally. Obtained results show that the powder densification process consists of two stages, and its mechanism during these two stages is not the same. During the first stage, densification occurs by grains coalescence, and air between the grains escape by open pores between particles. These open pores close in time by particles coalescence progress, and remaining air entrapped in polymer melt becomes air bubbles. Surface tension, viscosity, grains size, and temperature are the controlling parameters during first stage. A three-dimensional model is proposed for the densification of polymer powder during first stage. Second stage starts after bubble forming. Diffusion is the controlling phenomena during this stage. A diffusion-based model is used for the second stage of densification. By comparing with the other models, proposed model exhibits several advantages: it is proposed in three-dimensional and takes into account the nature of layer-by-layer powder densification. Model verification by experimental data obtained for densification of two different polymers shows a close agreement between model prediction and experiments. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10985/9894 2012-01-01T00:00:00Z ASGARPOUR, Monir KHAVANDI, Alireza TCHARKHTCHI, Abbas BAKIR, Farid KHELLADI, Sofiane During rotational molding, a loosely packed, low-density powder compact transforms into a fully densified polymer part. This transformation is a consequence of particles sintering. Powder compact density evolution of the polymer powder is measured experimentally. Obtained results show that the powder densification process consists of two stages, and its mechanism during these two stages is not the same. During the first stage, densification occurs by grains coalescence, and air between the grains escape by open pores between particles. These open pores close in time by particles coalescence progress, and remaining air entrapped in polymer melt becomes air bubbles. Surface tension, viscosity, grains size, and temperature are the controlling parameters during first stage. A three-dimensional model is proposed for the densification of polymer powder during first stage. Second stage starts after bubble forming. Diffusion is the controlling phenomena during this stage. A diffusion-based model is used for the second stage of densification. By comparing with the other models, proposed model exhibits several advantages: it is proposed in three-dimensional and takes into account the nature of layer-by-layer powder densification. Model verification by experimental data obtained for densification of two different polymers shows a close agreement between model prediction and experiments.